Ricardo Diaz´s Admiral from the mission "guardin angels" is undestructable.
There are also black Admiral´s in two telephone-missions, but in one mission, the have got a driver and in the oter mission the gate of the backyard isn´t opened enough to get it on the streets.

There´s also a Pony in black, it appears in the telephone mission which is at the Cherry Popper Ice Cream Factory, Little Havanna. But you can´t drive it out of the backyard, because the gate isn´t opened enough.